1. Field of the Invention
The present invention relates to a vehicle surroundings monitoring apparatus and more in particular to a vehicle surroundings monitoring apparatus suitable for detecting solid objects successively disposed along roads such as guardrails, side walls and the like.
2. Prior Arts
With increased number of vehicles and with increased number of traffic accidents, the conception of Advanced Safety Vehicle (ASV) is becoming one of primary strategies in designing a vehicle. In particular, an ASV technology raises the intelligence level of a vehicle through the state of the art electronic technologies. In recent years, various safety devices such as issuing an alarm to inform a vehicle driver of a likelihood of collision, stopping a vehicle, decreasing or increasing the speed of the vehicle by detecting a vehicle traveling ahead or an obstacle through a television camera, a laser-beam radar or the like, have been proposed.
The applicant of the present invention, in Japanese Patent Application Laid-open No. Toku-Kai-Hei 5-265547, have already disclosed a technique in which images taken by two stereoscopic cameras are transformed into distance images, these distance images being divided into lattice-like small regions at a prescribed interval to detect solid objects for each small region. Further, the applicant, in Japanese Patent Application Laid-open No. Toku-Kai-Hei 6-266828, have already proposed a technique wherein similarly data of solid objects per small region are extracted, these data being processed by a so called “Hough” transformation method to detect the solid objects such as side walls and guardrails aligned along roads.
However, according to these known arts, since the data of solid objects are processed by the “Hough” transformation method and the like, as a result, with respect to the solid objects provided along a curved road like guardrails, only their small portions located within a relatively short distance are recognized as straight lines, therefore it is much more difficult to recognize those objects in the distance.